Sixth WGS Satellite successfully Launches aboard Delta IV

August 8, 2013

A United Launch Alliance Delta IV Medium+ (5,4) launch vehicle successfully delivered the sixth Wideband Global Satcom satellite to Supersynchronous Transfer Orbit Wednesday night. The rocket blasted off from Space Launch Complex 37 at Cape Canaveral Air Force Station at 0:29 UTC on Thursday and performed a 40-minute ascent mission to achieve the desired orbit. WGS-6 was released at 1:09 UTC, its deployment coming just two and a half months after the launch of WGS-5. The launch was preceded by a clean countdown that got underway at 18:44 UTC. At T-5 Hours and 15 Minutes, the countdown clock was initiated, entering a planned hold as the launch team reported to console to get ready for the terminal countdown phase that started as soon as clocks started ticking. Out at Space Launch Complex 36, technicians were completing final hands-on work - closing out the launch vehicle and Mobile Service Tower structures. MST roll to launch position was completed earlier on Wednesday with first motion of the structure at 10:27am local time. The Fixed Service Structure of the pad was also prepared for launch before the launch pad was evacuated for propellant loading to start. Once coming out of the hold, the launch team started final preparations for the fueling sequence. Also, the Delta IV Redundant Inertial Flight Control Assembly, better known as RIFCA, the flight computer of the launcher, was powered up and aligned for flight. At T-4 hours and 52 minutes, the launch team gave the GO for Propellant Loading which started with the cold gas Chilldown of the Common Booster Core Liquid Hydrogen System starting at T-4:47. After chilldown of the transfer lines and the Common Core Booster Tank, -253-degree Celsius Liquid Hydrogen started flowing inside the first stage tank of the vehicle.

Photo: United Launch Alliance

Fueling of each propellant component goes through a complex sequence beginning with Ground Support Equipment and Tank Chilldown before propellant loading starts in slow fill in order to load the initial portion of the tank before fast fill can start. Once fast fill is complete, propellant loading enters topping.

CBC LH2 loading began fast fill at T-4:04. The Liquid Oxygen system chilldown phase started at T-4 hours and 15 minutes before entering fast fill 35 minutes later. Topping of the -183-degree Celsius oxidizer was initiated at T-3:00.

Photo: United Launch Alliance

While the first stage was loaded with 200,000kg of cryogenic propellants, the Delta Cryogenic Upper Stage began its fueling sequence to be loaded with 27,200kg of cryogenics. Hydrogen systems on the upper stage started Chilldown at T-3:54 followed by the initiation of Slow Fill 44 minutes later. LOX Chilldown on the Upper Stage started at T-2 hours 59 minutes with fueling commencing 13 minutes later. By T-90 minutes, propellant loading was complete and all tanks had reached topping without any major problems.

While propellant loading was in progress, the launch team put the other systems of the Delta IV through a series of tests including Telemetry and Communications checks to make sure the S- and C-Band Systems were ready for the mission. These tests also included the activation of the Command Receiver Decoder and Range Safety Checkouts of the Flight Termination System.

At T-40 minutes, the CBC RS-68 main engine completed Spin Start Pressurization and a Gimbal Steering Test. Steering tests were also completed by the RL-10B upper stage engine and the two Solid Rocket Motors with Thrust Vector Control capability.

Following the completion of fueling, the propellant fill & drain valves on both stages went through the prescribed cycle tests to verify they can be opened and closed on command. As clocks continued to tick down, a refined set of flight software was loaded into the computers of the launcher based on the latest trajectory modification to respond to conditions in the upper atmosphere. With the final countdown hold approaching, teams activated the Launch Pad Ordnances and made final preparations for the automated countdown sequence.

At T-4 minutes, the countdown entered its final built-in hold of 15 minutes with the option of an extension if required. During the hold, teams configured the WGS spacecraft, switching it to battery power and transitioning the satellite to its flight sequence.

The final Poll to head into the Automated Countdown Sequence was performed just before clocks started ticking again and verified that all systems were in the proper configuration for liftoff.

As the countdown resumed at T-4 minutes, the Launch vehicle was transferred to internal power. The process of securing the propellant tanks started with first stage LOX and LH2 at T-3 minutes. The two tanks of the second stage were secured at flight level at T-2:00 and T-1:20, respectively and teams performed a final check of the hydraulic system. All systems were in good shape when the countdown sequencer started-up at T-45 seconds and the two Solid Rocket Motors with TVC went through a Thrust Vector Control System test profile at T-25 seconds. 15 seconds before launch, the Launch Vehicle ordnances were armed and one second later the Radially Outward Firing Initiators were ignited to burn off residual Hydrogen during RS-68 ignition.

The Delta IV Terminal Countdown Sequencer assumed control of the countdown at T-8.5 seconds marking the start of the RS-68 ignition sequence beginning with the opening of the Main Hydrogen Valve at T-5.5 followed by Oxygen Valve Opening at T-2 seconds allowing the powerful engine to soar to flight speed being closely monitored by computers.

As the powerful RS-68 engine reached its liftoff thrust of 326,000 Kilograms, the ignition command was sent to the boosters - committing the rocket to flight.

Liftoff was on time at 8:29pm local time and the 66-meter Delta IV jumped off its pad with a total thrust of 674,000 Kilograms. After rising vertically for seven seconds, the launcher pitched and rolled onto its precise ascent trajectory - departing the space coast on a 100.97-degree launch azimuth, headed for a 24-degree orbit.

With all four boosters up and running, it took Delta IV just 36 seconds to pass Mach 1 with Maximum Dynamic Pressure occurring at T+50 seconds. The initial portion of the flight was nominal as Delta IV performed as expected heading uphill on its way to orbit. The two Solid Rocket Motors with fixed nozzles burned out at T+1:31 followed 1.2 seconds later by the TVC Solid Rocket Motors. The GEM-60 boosters were jettisoned in pairs at T+1:40 and T+1:42 and dropped away from the vehicle headed for a crash landing in the Atlantic Ocean.

Each GEM-60 Graphite Epoxy Motor provided 84,300kg of trust over the course of the burn during which it consumed 19,082kg of propellant.

With the solids gone, the launcher was powered by its RS-68 main engine. The mighty RS-68 is the most powerful Hydrogen engine in the world when flying in its RS-68A version that will become the regular engine of the Delta IV fleet once existing RS-68 engines have been flown. The RS-68 propelled the vehicle out of Earth's atmosphere allowing the payload fairing to be jettisoned. Fairing separation came at T+3:28 exposing the WGS-6 spacecraft as aerodynamic forces were no longer a concern. In the M+ (5,4) configuration, Delta IV uses a 5-meter payload fairing that is separated by pyrotechnic actuators.

After fairing separation, the RS-68 engine started its throttle segment to limit stress on the vehicle as it approached shutdown. Booster Engine Cutoff came at T+4 minutes and 8 seconds followed by stage separation 7 seconds thereafter. Immediately after separation, the nozzle extension of the RL-10B engine was deployed by an electromechanical system to get ready for upper stage ignition at T+4:27.

Ignition of the RL-10B that provides 11,220kg of thrust was nominal. The first burn of the upper stage was 16 minutes and 4 seconds in duration to reach an elliptical parking orbit with a low perigee of 185 Kilometers & an inclination of 25.6-degrees. Upper Stage performance was nominal and the vehicle reached an orbit of 185 by 6,878 Kilometers at an inclination of 25.6 degrees.

Following RL-10B shutdown at around T+20:32, the launcher entered a short coast phase of 7 minutes and 50 seconds.

Photo: United Launch Alliance

Photo: United Launch Alliance Webcast

SRM Separation

Photo: United Launch Alliance Webcast

Fairing Separation

This coast accomplished two things - it allowed the vehicle to climb uphill so that the next burn would not only increase the apogee but also add 200 Kilometers to the perigee altitude. Also, the coast set up the proper position of the apogee passage in preparation for orbit raising maneuvers by WGS-6 itself. During the coast, the upper stage performed attitude maneuvers.

The second burn of the Delta Cryogenic Upper Stage began on time at about T+28:22 and was 3 minutes and 8 seconds in duration. The burn was as expected and delivered the stack to a 440 by 66,830-Kilometer Orbit at an inclination of 24.0 degrees which is very close to the target orbit of 441.7 by 66,941.5 Kilometers at 24.0°.

After shutting down, the second stage performed a re-orientation to achieve the proper attitude for spacecraft separation. WGS-6 was sent on its way just after passing the 40.5-minute mark of the flight. Spacecraft separation was as planned and marked the successful completion of Delta IV's mission, although the upper stage still had its nominal Contamination and Collision Avoidance Maneuver on its agenda.

The WGS-6 mission was Delta's 363rd flight since the start of the program back in 1960. It was the 23rd flight of a Delta IV and the fourth mission of the M+ (5,4) version as WGS 3 through 5 were also launched on this version. It was the second Delta IV flight after a flight in May that orbited the WGS-5 spacecraft.

For WGS-6, a busy few weeks are on tap as the vehicle has to complete initial commissioning and orbit raising operations. It will perform a number of maneuvers to achieve Geostationary Orbit to start deployments and checkouts that will last several months. Once checkouts are complete, the satellite will be moved from the checkout location to its operational slot in Geostationary Orbit. Orbit adjustments will take about 106 days, checkouts are planned to take 49 days and the drift to the operational location will take another 24 days. A detailed overview of the Wideband Global Satcom system can be found below.

WGS-6 Payload Information

WGS-6 – The Wideband Global Satcom 6 Satellite is the third in a series of improved WGS satellites providing communications for military operations including unmanned drones used for surveillance and intelligence gathering operations around the globe. Other secure communications are also provided by the Vehicle.

WGS-6 was financed by Australia which will allow the country global access to the WGS fleet for worldwide secure communications capability.

The WGS-6 Spacecraft weighs around 5,987kg and features two deployable solar arrays with a span of 41 meters once deployed in orbit to provide 11 kilowatts of end-of-life power. It is based on Boeing's 702HP satellite bus that is capable of hosting powerful communications payloads with payload power of up to 18kW. The satellite utilizes dual and triple-junction gallium arsenide solar cells. WGS-6 features a liquid-propulsion system centered around the R-4D engine.

The R-4D engine is a Monomethylhydrazine/Nitrogen Tetroxide Engine that provides 490 Newtons of thrust. The engine is 0.55 meters long and 0.28 meters in diameter with an unfueled mass of 3.63 kilograms. The engine provides a specific impulse of 312s, has a thrust to weight ratio of 13.7 and operates at a chamber pressure of 6.9 bar. The original RD-4 was developed as an attitude control thruster for the Apollo Service and Lunar Lander modules. RD-4 engines were built by Kasier Marquardt

Photo: Boeing

WGS-6 during Production

In addition, WGS satellites are equipped with four xenon ion propulsion system thrusters. XIPS-25 provides a thrust of 165 Millinewtons. This system can be used for Stationkeeping or drifting in Geostationary Orbit and for satellite momentum control. Using ion thrusters is more efficient in terms of fuel consumption and can extend a satellite's lifetime beyond its limited fuel supply.

WGS-6 hosts a powerful communications payload for secure and fault-proof communications. It provides steerable spotbeams that can reach any position within the satellite’s field of view. Two-way Ka- (1GHz) and X-Band (500MHz) communications are supported by the Spacecraft which also provides a capability to convert signals from one to the other with its onboard systems. WGS-6 provides unprecedented data rates of 2.1 to 3.6 Gbps. A total of 19 independent coverage areas that can be used throughout the field of view of each satellite. These include 8 steerable X-Band beams provided by separate transmit and receive phased arrays as well as 10 steerable Ka-Band beams that are formed by steerable, diplexed gimbaled dish antennas.

Image: Boeing

The remaining coverage area is an X-Band Earth Coverage beam. WGS can tailor coverage in near-real time and connect X-Band and Ka-Band Users anywhere within the field of view. Block II satellites also provide a high-bandwidth radio frequency bypass capability.

The WGS Fleet is controlled by four Army Wideband Satellite Operation Centers that receive telemetry and send commands to up to three satellites per center. Telemetry and command links are available via X- and Ka-Band. Spacecraft platform control and stationkeeping maneuvers as well as orbital planning is accomplished by the 3rd Space Operations Squadron stationed at Shriver Air Force Base.

The WGS constellation is replacing the Defense Satellite Communications System which has been operating for several decades and is phasing out as the new vehicles are entering their respective orbital positions.

Delta IV declared Ready to Launch with WGS-6 Satellite

August 6, 2013

*File Image* - Photo: United Launch Alliance

A United Launch Alliance Delta IV rocket has been approved for launch early on Thursday (UTC) after a clean Launch Readiness Review that was performed on Tuesday. Delta IV will fly in its Medium+ (5,4) configuration to deliver the Wideband Global Satcom 6 Satellite to Supersynchronous Transfer Orbit. The launch window opens at 00:29 UTC (8:29pm local on Wednesday) and stretches 49 minutes. Mission Managers met Tuesday morning to discuss the status of countdown preparations and look at all systems involved in the Delta IV launch. It was determined that everything was ready for launch and the official go-ahead to press into countdown operations was given. The official weather forecast provided by the 45th Weather Squadron is also very positive. Meteorologists have issued an 80% chance of favorable conditions during the launch window. Primary concerns are violations of the cumulus cloud rule due to coastal showers. "In this weather regime, isolated showers may develop along the East Central Florida coast as the sea breeze first develops, but then progress inland with the sea breeze. Thunderstorms will develop inland and along the west coast of Florida, but upper level winds will be from the northeast keeping anvils from inland thunderstorms away from the east coast. Overall, conditions are favorable for launch," the forecast of the 45th Weather Squadron said. Countdown Operations will begin on Wednesday as the launch team reports to console and teams start final work at Space Launch Complex 37 at Cape Canaveral Air Force Station. The first step is the retraction of the large Delta IV Mobile Service Tower, moving it to its launch position at a safe distance to the Delta IV Launcher. The terminal countdown begins at T-5 hours and 15 minutes with the initialization of the countdown and activation of the Delta IV Flight Control Assembly.

The Launch Area will be evacuated shortly thereafter and the launch team will make final preparations for Cryogenic Tanking. At T-4:50, Common Booster Core Liquid Oxygen Loading Operations will get underway with Ground Support Equipment pressurization and chilldown before propellant starts flowing inside the CBC’s LOX Tank going through Slow-Fill and Fast-Fill before reaching Topping Mode.

Liquid Hydrogen Loading of the CBC begins at T-3 hours and 40 minutes and also goes through these steps. The Launch Team will receive periodic weather briefings closely monitoring conditions and the status of all weather rules.

The second stage tanking sequence begins at T-2:55 for LOX and T-2:40 for LH2. While fueling is in progress, the launch vehicle will be put through communications and telemetry checkouts and command receiver decoder testing. At T-50 minutes, the RS-68 engine of the launcher will go through Engine Spin Start Pressurization and a Gimbal Steering Check. Around that time, the launcher will undergo an inspection for any ice build-up following tanking. Just before reaching the T-4-Minute Hold, teams make final preparations for the automated sequence and arm the launch pad ordnances. The hold can be extended in the event of unfavorable weather or any technical problems the launch team needs to address. During the hold, the final GO/No GO Polls are performed by the launch team.

Once clocks start ticking, again, Delta IV transfers to internal power and the Safe and Arm Switches are being armed for liftoff. Three minutes ahead of launch, the LOX and LH2 Tanks of the launcher are being secured at flight level.

Second stage securing starts one minute later. In addition, the hydraulic system of the vehicle will be checked one final time at this point. At T-50 seconds, all tanks will be at flight level and all ground support equipment will be secured as well. 45 seconds before T-0, the Launch Enable Command is sent. At T-25 seconds, the twin Solid Rocket Motors are going through a Thrust Vector Control System Check and the Launch Vehicle Pyrotechnics are armed 10 seconds later. 14 seconds ahead of liftoff, the Radially Outward Firing Initiators are activated to burn any residual Hydrogen. The Terminal Countdown Sequencer assumes control of the countdown at T-8.5 seconds and at T-5.5 seconds, the RS-68 opens its main Hydrogen Valve followed by the LOX Valve at T-2 seconds to go to Full Thrust. At T-0.04 seconds, Delta IV is committed to launch with Booster Ignition occurring simultaneously with Hold-Down Release and liftoff of the launch vehicle.

Following liftoff, Delta IV will fly a mission profile closely resembling that flown on its most recent flight in May when it delivered WGS-5 to SSTO. The flight will take 40 minutes from liftoff to spacecraft separation. The four Solid Rocket Motors will burn for about 90 seconds for jettison 100 seconds into the flight. The Common Booster Core will burn for 4 minutes and 8 seconds, after which the first stage separates and the second stage begins its first burn to deliver the vehicle to a parking orbit. At T+20:32, the second stage shuts down to allow the vehicle to coast uphill for eight minutes in order to be able to achieve a sufficient perigee on the injection orbit. The second burn of the Upper Stage is just over three minutes in duration and raises the apogee to nearly 67,000 Kilometers. Spacecraft separation occurs at T+40:38.

Delta IV set to Launch next Wideband Global Satcom Satellite

July 31, 2013

Moving along in a busy manifest of launches lined up for 2013, United Launch Alliance is preparing for two Delta IV launches in August. First, on August 8, a Delta IV Medium+ (5,4) will blast off from Cape Canaveral Air Force Station, Florida, to deliver the Wideband Global Satcom 6 satellite to Orbit. Later in August, on the 28th, a Delta IV Heavy Rocket will launch from Vandenberg Air Force Base, California, carrying a classified payload for the US National Reconnaissance Office.

The launch of WGS-6 will come just two and a half months after the successful launch of WGS-5 that occurred on May 25, 2013 when a Delta IV M+ (5,4) performed a flawless ascent mission launching from Space Launch Complex 37 at Cape Canaveral Air Force Station. Even before that Delta rocket took off, the launcher for the WGS-6 mission was already at the Space Coast, being readied for integration.

Preparations for the launch of WGS-6 got underway with the arrival of the Common Booster Core of the Delta IV launcher at Cape Canaveral that occurred in February 2013. The remaining launcher components were also delivered well before the build-up of the Delta IV began.

WGS-6 was shipped to Cape Canaveral in mid-May 2013 being delivered via a cargo aircraft transporting the satellite from Boeing's El Segundo, California manufacturing facility. With WGS-6 at the Space Coast, final processing of the satellite began inside the Astrotech Facility, Titusville.

Image: United Launch Alliance

WGS-6 underwent final inspections and reconfigurations as well as hazardous processing including propellant loading. Afterwards, the satellite was encapsulated in the protective 5-meter Delta IV Payload Fairing to get ready for its rollout to the launch complex.

Delta IV completed integration earlier with its Common Booster Core being the first component to be integrated on the launch pad. The four Boosters were attached to the CBC and the interstage adapter along with the Cryogenic Upper Stage were installed atop the vehicle ahead of the start of testing.

Photo: United Launch Alliance

On July 17, the assembled Delta IV rocket was exposed at the launch pad for a Wet Dress Rehearsal. The launch vehicle was fully fueled as part of a full countdown rehearsal involving the launch team and all support personnel. The WDR served as systems test confirming that all propellant systems were performing as expected without any leaks or other problems. After the WDR was complete, the Mobile Service Gantry was moved back around the launch vehicle in preparation for the installation of the payload stack.

WGS-6 encapsulated in the Fairing was rolled to the launch complex on July 23. Once arriving at SLC-37, the stack was carefully hoisted and positioned atop the Delta IV for installation. Structural, electrical and data connections were put in place to complete the integration process and set the stage for integrated testing. Integrated testing of the launcher and payload include countdown and flight simulations to verify the computers send the correct commands at the appropriate times to verify the vehicle is ready for its flight.

The satellite will also complete flight simulation tests as well as battery charging for the mission as the launch approaches.

Liftoff is set for August 8, 2013 during a 49-minute launch window opening at 0:29 UTC.

Please consider supporting this website by making a small donation. Our reader's support keeps the site open & improving.